Since the 15th August in 2015 we have been running on a Hybrid solar system, solar by day and Grid by night.
Oddly enough since the day we switched the solar on we have not had a single day's load shedding.
The system has worked fairly well, as soon as the sunlight comes in over the mountains the system kicks over to solar, some days it runs for an hour or so and then cuts back to grid because the light is just too low. In general the winter days it ends up being a cut over to solar at between 8 and 9 am, then it stays on solar until about 5 or 6 pm.
Below is typically what I see on the daily graphs. The very flat line at 230 volts is the inverter output, the horrible unstable line is the grid power. Below you can see that we ran on Solar from 8am to about 18h00
I made a mathematical calculation for projected savings, it seems I was not far off..
If I look at the year period from September 2015 to August 2016 and compare that with the year period September 2014 to August 2015, we made a 20% saving on power consumption. At the current power cost that equates to R 3140.00.
If I look at the year period from September 2013 to August 2016 and compare that with the year September 2015 to August 2016, we made a 25% saving on power consumption. At the current power cost that equates to R 4 146.00.
The reason I compare the previous year is that I started fiddling with the solar system from January 2015 already, so part of 2015 was already seeing the power savings.
From my previous blog you can see I predicted a R 3 900.00 rand saving, if I take the two above numbers and average them I am at R 3 600.00 odd rand. Pretty darn close I think.
What is not factored in to the "savings" is the additional power we have used, simply because it was available. For instance in Summer we ran the air conditioner on some of the hot days, this was never done in the past. Also my cost predictions were done on the current power cost at the time, come next year this time we will have a better ROI simply because the cost of power has gone up.
The initial investment value has gone up since the initial installation, I added a few extra WATTS of Panel.
The complete cost of the system was R 31 074.00 At the rate of R 3 600.00 its going to take 6 odd years to pay itself off, that being on an assumption that power increases by cost at 10% per year.
I predict that my Batteries my well be in need of replacement in 6 years so that would start the repayment cost again, this time the ROI value will be a fraction of the initial investment cost.
